Automotive vehicles incorporate a variety of restraint systems to provide for the safety of vehicle occupants. For example, it is known in the vehicle art to provide various types of seat belts or restraint systems for restraining an occupant in his or her seat and providing controlled deceleration of portions of the body to limit the forces applied to the occupant's body during rapid deceleration of a vehicle from a cause such as a collision. Various types of seat belts and restraint systems have been used in automobiles, trucks, and other vehicles and are commonly known today.
Known seat belt systems typically used in commercially available production vehicles are three-point restraint systems with a lap belt and a shoulder belt extending over one shoulder of the occupant and connecting with the lap belt. The lap belts are anchored at one end, to the seat or to the vehicle adjacent the seat. The shoulder belts are connected at one end to the vehicle or to the seat and at the other end to the lap belt or lap belt buckle mechanism.
Four, five, and six-point restraint systems are among some of the seat belt and restraint systems that are particularly utilized in off-road type vehicles and other sport-type vehicles in order to provide additional restraint for occupants over two and three-point restraint systems. These seat belt systems tend to have multiple adjustable cinching mechanisms and are awkward and difficult to operate and properly position on an occupant. They also may be less comfortable and more complex due to the multiple mechanisms and therefore not amenable to quick donning and doffing on multiple occasions as may be required in a passenger vehicle.
Of particular interest to the automotive industry today is the 4-point seat belt restraint system. Studies indicated that the use of 4-point belts may help reduce chest injuries especially in elderly occupants of motor vehicles. However, there are concerns that some occupants may not like the 4-point seat belt restraints and therefore may elect to be unrestrained rather than wear a 4-point seat belt. This would expose occupants to potentially much higher risk of injury in a crash than if they were restrained. Customers may be provided with an option to choose between a 3-point seat belt arrangement and a 4-point seat belt arrangement, for those who do not like 4-point seat belts, could resolve this issue.
In addition, early research with specialized crash test dummies which simulate a pregnant woman in her third trimester showed higher intrauterine pressure when a 4-point belt was used when compared with a 3-point belt. While it is unknown whether the pressure was high enough to cause injury to a baby in the womb, it was considered desirable to have a retrofit kit for pregnant women to get the buckle of the 4-point belt off of the abdomen.
Research has further shown that 4-point belts are fundamentally different from 3-point belts in the way the body loads them in a crash. Accordingly, any system that provides for selection between a 3-point seat belt system and a 4-point seat belt system would require a method of altering the geometry, lap belt mobility, and shoulder belt load limit of a 4-point belt system to allow its safe use as a 3-point belt. Thus in any reversible system the 4-point belt arrangement would require two shoulder belts which are closer to the centerline of the seat than a 3-point belt and may require a different load limit in each configuration.
Accordingly, a need exists today for a seat belt arrangement that is reversible between a 3-point arrangement and a 4-point arrangement. Such a system must be comfortable to the wearer and would thus be able to have an altered belt geometry. Accordingly, the ideal system would not only allow reversibility between the 3-point belt arrangement and the 4-point belt arrangement but would also be comfortable to the user in either configuration. Additionally, the properties of the system components would be adjustable and adaptable to the arrangement selected, whether that is a 3-point or a 4-point arrangement.